ABSTRACT
Real physical bodies exhibit linear viscoelasticity at low stress and strain values. When these parameters increase, a noticeable deviation from the linear viscoelastic behaviour is observed. To clarify the cause of this phenomenon, this chapter considers the molecular-kinetic nature of deformation and relaxation of amorphous bodies. To simulate the spectrum of relaxation times, it is necessary to connect in parallel a set of Maxwell models with different values of the elasticity modulus of the spring and the viscosity of the liquid. The relaxation nature of viscoelasticity manifests itself as a dependence of the mechanical behaviour of the material on the time of observation or on the time of the force action. The basic elements of mechanical models are a spring and a piston in a viscous liquid. The Voigt–Kelvin model predicts the flow in time, that is the relaxation nature of reversible deformation in contrast to the Maxwell model, within which reversible deformation develops and relaxes instantaneously.
